The present invention relates to an automatic vehicle tire pressure measurement/adjustment system for measuring and adjusting the tire pressure of a vehicle, as well as a corresponding automatic vehicle tire pressure measurement/adjustment method. Although applicable to any vehicle, the exemplary embodiments of the present invention are explained with reference to a motor vehicle, such as, for example, a passenger car.
In general, it is believed that to achieve optimum driving characteristics, the tires of a vehicle should be inflated to a tire pressure that must lie, depending on specific parameters such as, for example, payload weight, air temperature, tire temperature, maximum speed, road condition, etc., within a narrow pressure range, such as, for example 2.8 barxc2x10.05 bar.
Tire pressure is a critical parameter, in particular, for the performance of motor vehicle systems such as, for example, the antilock braking system (ABS), automatic slip control system (ASR), and electronic stability program (ESP), so that a tire pressure monitoring system or regular checking and correct adjustment of the tire pressure, for example following any change in loading, can contribute appreciably to a gain in vehicle safety.
Certain companies may have been offering tire pressure monitoring systems that are built into the vehicle and that warn the driver when the pressure in one or more tires is too low or too high, such as, for example, by way of a corresponding warning light.
Such tire pressure monitoring systems may operate on the basis of estimates or direct measurements. They may operate almost continuously over time, and can warn the driver immediately in the event of a pressure loss.
A substantial disadvantage of these systems, however, is the reliability achievable so far that can be offered at the present day at reasonable cost. In addition, the driver must himself or herself take action once a pressure loss has been recognized, and undertake corresponding measures. This may be troublesome, since tire pressure correction requires an intervention that is strenuous (especially for older persons) and may be associated with soiling of the hands.
The tire pressure adjustment systems set up at filling stations may be in poor condition, with the result that the desired tire pressure cannot be established accurately.
Accurate determination of the nominal tire pressure presents a further problem. This is may be done by way of tables displayed at the filling station or in the vehicle. Automatic units located permanently at filling stations, with pressure measurement functions and pressure calculation functions, are not believed to be presently available.
Since present-day filling stations are developing more and more into meeting points and service locations, it would be desirable if an automatic tire pressure measurement/adjustment system were also part of a kind of xe2x80x9call-round service packagexe2x80x9d (along with further services such as automatic fueling, general cleaning, fluid checks, etc.).
The automatic vehicle tire pressure measurement system of the present invention and the corresponding automatic vehicle tire pressure measurement method of the present invention are believed to have the advantage as compared to other approaches to the problem that they make possible automatic vehicle-related tire pressure monitoring without troublesome manual action or calculation by the driver.
This is a convenience system for vehicle servicing. In principle, it can be used to adjust the tire pressure automatically each time a filling station is visited, thus guaranteeing optimum vehicle performance.
The exemplary embodiment of the present invention provides an automatic tire pressure measurement/adjustment system for a vehicle at a (motor) vehicle service location (e.g. a filling station), although in purely theoretical terms it can also be part of the vehicle itself (this variant of the system would be conceivable in particular for commercial vehicles that have a compressed-air supply system). The exemplary embodiment of the present invention provides, in particular, for communication between the vehicle and the vehicle tire pressure measurement/adjustment system in order to determine a tire pressure that is optimum for the specific vehicle.
The exemplary embodiment of the present invention concerns the automatic measurement and adjustment of tire pressure on the basis of vehicle-related data such as, for example, previous travel conditions, payload weight, etc. The measured tire air temperature, as well as non-vehicle-related parameters such as, for example, intended maximum speed, road condition on the route of travel, outside air temperature, and weather forecast, can also be taken into account by way of corresponding inputs when the nominal tire pressure is determined.
According to an exemplary embodiment, the vehicle-specific parameter is selected from the following group: vehicle model, tire type (e.g. manufacturer or summer/winter tires), vehicle mass, number of vehicle occupants, vehicle operating information.
According to another exemplary embodiment, a second communication device is provided that is connectable to the determination device for input of at least one non-vehicle-specific parameter, the determination device being configured such that it determines the nominal tire pressure in consideration of at least one non-vehicle-specific parameter.
According to another exemplary embodiment, the non-vehicle-specific parameter is selected from the following group: intended maximum speed, road condition on the intended route of travel, outside air temperature, and weather forecast.
According to another exemplary embodiment, the tire pressure measurement device has a tire air temperature measurement device for measuring the tire air temperature, the determination device being configured such that it determines the nominal tire pressure in consideration of the measured tire air temperature. Errors in establishing the air pressure in the tires, e.g. release of air because a heated tire simulates a higher pressure, can thereby be prevented.
According to another exemplary embodiment, the automatic handling unit has a valve cap threader device for screwing the valve cap on and off.
According to a further preferred development, the automatic vehicle tire pressure measurement/adjustment system is installed at a filling station in the vicinity of a fuel pump and can be activated while the vehicle is being fueled. This has the advantage that the tire pressure check then involves absolutely no additional effort from the driver""s point of view.
According to another exemplary embodiment, the first communication device is connectable to an onboard computer of the vehicle. The vehicle-specific parameter(s) can thus be taken from a memory belonging to the onboard computer or can be modified therein, e.g. if one tire type is replaced with a different tire type that requires different pressures.
According to another exemplary embodiment, the first communication device is connectable to a mass estimation device, located in the vehicle, with which the vehicle mass can be estimated, preferably from the vehicle""s curb weight and a drive torque needed to achieve a specific acceleration.
According to another exemplary embodiment, a gradient correction device is provided to determine a gradient correction for the mass estimation device.
According to another exemplary embodiment, the determination device is configured such that it determines the nominal tire pressure in consideration of a GPS altitude measurement.
According to another exemplary embodiment, the determination device is configured such that it determines the nominal tire pressure on the basis of a table stored therein.
According to another exemplary embodiment, the automatic handling unit is movable along a rail device. It is thus sufficient to make one mechanical robot available for all the tires of a vehicle.
According to another exemplary embodiment, a transfer device that is connectable to the determination device is provided, and is configured such that it transfers the nominal tire pressure, and/or a difference between the nominal tire pressure and the existing tire pressure, to the vehicle for storage and/or display therein.
According to another exemplary embodiment, there is provided in the vehicle an analysis device which is configured such that it analyzes the frequency and/or magnitude of the differences transferred and prepares therefrom, in consideration of any possible change in the differences, an advisory as to tire problems. For example, a pressure loss of 0.1 bar/month is usual. If losses are greater, there may be a leak, about which the driver is then informed.
According to another exemplary embodiment, the determination device is arranged outside the vehicle and the communication device is connectable thereto via a wireless interface, preferably an infrared interface or a radio interface.
According to another exemplary embodiment, the determination device is arranged inside the vehicle and is connectable to the tire pressure adjustment device via a wireless interface, preferably an infrared interface or a radio interface.